The present disclosure relates generally to the field of micro-electromechanical system (MEMS) devices and, more particularly, to MEMS switches and associated switch arrays.
Micro-electromechanical systems have been exploited as viable alternatives for existing electromechanical devices such as relays, actuators, valves and sensors. MEMS devices are potentially low cost devices, due to the use of microelectronic fabrication techniques. New functionality may also be provided because MEMS devices can be dimensionally smaller than existing electromechanical devices.
Many potential applications of MEMS technology utilize MEMS actuators. For example, many sensors, valves and positioners use actuators for movement. If properly designed, MEMS actuators can produce useful forces and displacement, while consuming reasonable amounts of power. MEMS actuators, in the form of micro-cantilevers, have been used to apply rotational mechanical force to rotate micro-machined springs and gears. Piezoelectric forces have also been employed to controllably move micro-machined structures. Additionally, controlled thermal expansion of actuators or other MEMS-based components has been used to create forces for driving micro-devices.
Micro-machined MEMS electrostatic devices, which use electrostatic forces to operate electrical switches and relays, have also been created. Various MEMS relays and switches have been developed with relatively rigid cantilever members, or flexible flaps separated from an underlying substrate in order to make and break electrical connections.
Many MEMS switches have inherently low current carrying capacity in the closed position and can tolerate only a small voltage in the open position, which makes these switches more susceptible to damage than macroscopic mechanical switches. Recently, arrays of MEMS switches have been used to divide the current, voltage, or both across a number of MEMS switches. A series configuration would divide voltage and a parallel configuration would divide current. However, these MEMS arrays are substantially impacted by the failure of individual MEMS switches, which limits the usefulness of the overall arrays.
Despite their suitability for their intended purposes, there nonetheless remains a need in the art for improved MEMS arrays. It would be particularly advantageous if these MEMS arrays were more tolerant of failure of an individual MEMS switch. It would be further advantageous if such arrays continued to operate as intended despite the failure of more than one MEMS switch in either the short circuit or open circuit mode of failure.